There is a certain amount of wax ranging from 1% to 50% in crude oil produced everywhere. For example, in China the wax contained in crude oil amounts to more than 10%. The yield of an oil well is affected negatively by wax precipitating from oil and accumulating on the inside wall of the oil pipes. As a result, wax even blocks the oil well.
Although traditional wax-proof and wax-cleaning methods are somewhat effective, they consume a great deal of energy, require additional equipments and professional operators, and make the exploitation process complicated and the oil product cost high. For example, wax proof methods adding chemical preparations, thermodynamic methods for raising oil temperature, and wax-cleaning such as pouring hot water, vapor or hot oil into the oil well or scraping away the wax mechanically from oil pipe wall, all lead to the high oil production cost and make the maintenance of oil well complicated.
The inventor of this invention developed earlier in 1984 a new device connected in series with the oil pipe of an oil well to suppress the process of wax precipitation, it is effective to some extent, but said device contains only radially oriented permanent magnets, magnetic field generated therefrom can not be concentrated highly in the central area of oil flow, so it is unable to meet the need of oil wells where a strong magnetic field is required. Moreover, such a device can not be connected in series with the sucker rod used in oil-pumping wells as necessary in practice.
The main object of the present invention is to present an essentially improved permanent-magnet wax-proof device which highly concentrates in the main area of oil flow the magnetic field produced by radially oriented permanent magnets, and provides thus a series of more effective devices.
The further important object of the invention is to provide a kind of permenant-magnet wax-proof device which can particularly be connected in series with very long and thin sucker rods within the oil pipe and which has the advantage of being small in size, light in weight, and easy to be installed and dismantled. In addition, a combination use of all the above mentioned permanent-magnet wax-proof devices of this invention will lead to very good wax-proof effects as will be illustrated in the following description.
Other advantages and applications of the invention will become apparent from the following description when read in conjuction with the accompanying drawings.